In a motor such as a brushless motor, a rotation sensor is provided in order to detect a rotational angle of the motor, and a motor current is controlled in accordance with the rotational angle of the motor, which is detected by the rotation sensor. In this control system, when the rotation sensor is broken down, and a normal information item of the rotational angle of the motor is not obtained, a motor control operation cannot be continued. In a conventional art, as described in Patent Document 1, duplexed sensors are provided with respect to the sensor fault, and when a broken wire or a short circuit is caused in each of the sensors, a method, which detects an abnormality of the sensors, is used.